2008-12-18  Kenneth Zadeck <zadeck@naturalbridge.com>

	PR rtl-optimization/37922
	* dse.c (bb_info): Added regs_live field.
	(look_for_hardregs): New function.
	(replace_read): Added regs_live parameter and code to check that
	shift sequence does not clobber live hardregs.
	(check_mem_read_rtx): Added parameter to replace_read.
	(dse_step1): Added regs_live bitmap and initialize it.
	(rest_of_handle_dse): Added DF_NOTES problem and earlier call to
	df_analyze.
	* df-problems.c Renamed to 
	df_simulate_initialize_backwards.
	(df_simulate_one_insn): Renamed to
	df_simulate_one_insn_backwards.
	(df_simulate_artificial_refs_at_top): Renamed to 
	df_simulate_finalize_backwards.
	(df_simulate_initialized_forwards,
	df_simulate_one_insn_forwards,
	df_simulate_finalize_backwards): New functions.
	* df.h (df_simulate_artificial_refs_at_end): Renamed to 
	df_simulate_initialize_backwards.
	(df_simulate_one_insn): Renamed to
	df_simulate_one_insn_backwards.
	(df_simulate_artificial_refs_at_top): Renamed to 
	df_simulate_finalize_backwards.
	(df_simulate_initialized_forwards,
	df_simulate_one_insn_forwards,
	df_simulate_finalize_backwards): New functions.
	* ra-conflict.c (global_conflicts): Renamed
	df_simulate_artificial_refs_at_end to
	df_simulate_initialize_backwards.
	* sel-sched.c (propagate_lv_set): Renamed df_simulate_one_insn to
	df_simulate_one_insn_backwards.
	* ifcvt.c (dead_or_predicable): Renamed
	df_simulate_artificial_refs_at_end to
	df_simulate_initialize_backwards. Renamed df_simulate_one_insn to
	df_simulate_one_insn_backwards.
	* recog.c (peephole2_optimize): Ditto.
	* rtl-factoring (collect_pattern_seqs, clear_regs_live_in_seq): Ditto.

2008-12-18  Kenneth Zadeck <zadeck@naturalbridge.com>

	PR rtl-optimization/37922
	* g++.dg/torture/pr37922.C: New test.

From-SVN: r142809